ES2353544A1 - Cementitious composite with carbon nanofibers for monitoring deformations - Google Patents
Cementitious composite with carbon nanofibers for monitoring deformations Download PDFInfo
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- ES2353544A1 ES2353544A1 ES200901735A ES200901735A ES2353544A1 ES 2353544 A1 ES2353544 A1 ES 2353544A1 ES 200901735 A ES200901735 A ES 200901735A ES 200901735 A ES200901735 A ES 200901735A ES 2353544 A1 ES2353544 A1 ES 2353544A1
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
- C04B28/02—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing hydraulic cements other than calcium sulfates
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B14/00—Use of inorganic materials as fillers, e.g. pigments, for mortars, concrete or artificial stone; Treatment of inorganic materials specially adapted to enhance their filling properties in mortars, concrete or artificial stone
- C04B14/02—Granular materials, e.g. microballoons
- C04B14/022—Carbon
- C04B14/026—Carbon of particular shape, e.g. nanotubes
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B14/00—Use of inorganic materials as fillers, e.g. pigments, for mortars, concrete or artificial stone; Treatment of inorganic materials specially adapted to enhance their filling properties in mortars, concrete or artificial stone
- C04B14/38—Fibrous materials; Whiskers
- C04B14/386—Carbon
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B7/00—Measuring arrangements characterised by the use of electric or magnetic techniques
- G01B7/16—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring the deformation in a solid, e.g. by resistance strain gauge
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L1/00—Measuring force or stress, in general
- G01L1/20—Measuring force or stress, in general by measuring variations in ohmic resistance of solid materials or of electrically-conductive fluids; by making use of electrokinetic cells, i.e. liquid-containing cells wherein an electrical potential is produced or varied upon the application of stress
- G01L1/205—Measuring force or stress, in general by measuring variations in ohmic resistance of solid materials or of electrically-conductive fluids; by making use of electrokinetic cells, i.e. liquid-containing cells wherein an electrical potential is produced or varied upon the application of stress using distributed sensing elements
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01M5/00—Investigating the elasticity of structures, e.g. deflection of bridges or air-craft wings
- G01M5/0041—Investigating the elasticity of structures, e.g. deflection of bridges or air-craft wings by determining deflection or stress
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01M5/00—Investigating the elasticity of structures, e.g. deflection of bridges or air-craft wings
- G01M5/0083—Investigating the elasticity of structures, e.g. deflection of bridges or air-craft wings by measuring variation of impedance, e.g. resistance, capacitance, induction
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
- C04B2111/90—Electrical properties
- C04B2111/94—Electrically conducting materials
Abstract
Description
Composite cementicio con nanofibras de carbono para monitorización de deformaciones.Cementitious composite with carbon nanofibers for deformation monitoring.
La presente invención se encuadra en el campo de la construcción, y más particularmente se refiere a tecnología de los materiales y nanotecnología.The present invention falls within the field of construction, and more particularly refers to technology of Materials and nanotechnology.
La función de percepción de la deformación fue desarrollada inicialmente utilizando fibras de acero y fibras de carbono de uso general, siendo objeto de estudio con creciente interés hasta el presente con la introducción de nuevos parámetros.The deformation perception function was initially developed using steel fibers and fibers of General purpose carbon, being studied with increasing interest so far with the introduction of new parameters
En la década de los noventa se patentaron diversos procedimientos para aplicar esta técnica. Entre los antecedentes conocidos destacan las patentes americanas US5817944 y US6079277. Tales invenciones consisten en el uso de fibras de carbono dispersadas en matrices de cemento para medir la deformación que sufren al ser sometidas a un esfuerzo externo sin necesidad de llevar ningún sensor embebido o adherido, mediante la medida de las variaciones de su resistencia eléctrica durante el proceso.In the nineties they were patented Various procedures to apply this technique. Between the known background highlights US patents US5817944 and US6079277. Such inventions consist of the use of fibers of carbon dispersed in cement matrices to measure deformation who suffer when subjected to an external effort without the need for carry any embedded or adhered sensor, by measuring the variations of its electrical resistance during the process.
Los principales inconvenientes que plantean estos antecedentes son:The main drawbacks they pose This background is:
- \bullet?
- La dispersión de estas adiciones en la matriz cementicia es una labor compleja y muy delicada a la hora de obtener los resultados deseados ya que implica el uso de aditivos adicionales y varias etapas previas a la propia incorporación a la matriz.The dispersion of these additions in the cement matrix is a complex and very delicate work to the time to obtain the desired results since it implies the use of additional additives and several stages prior to one's own incorporation into the matrix.
- \bullet?
- La fibra de carbono ofrece una moderada área de contacto con la matriz cementicia, propiedad que es importante a la hora de que el material funcione.Carbon fiber offers a moderate area of contact with the cement matrix, property that is important when the material works.
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Con la intención de mejorar tales inconvenientes surge esta invención que ofrece las siguientes mejoras respecto a los materiales que emplean fibras de carbono:With the intention of improving such inconveniences this invention arises that offers the following improvements with respect to Materials that use carbon fibers:
- \bullet?
- La incorporación de nanofibras en la matrices cementicias es un proceso sencillo y reproducible ya que su dispersión en la matriz es directa, lo cual garantiza poder llevar a cabo la monitorización de la deformación de forma óptima.The incorporation of nanofibers in cementitious matrices it is a simple and reproducible process since that its dispersion in the matrix is direct, which guarantees power carry out form deformation monitoring optimal
- \bullet?
- El área de contacto matriz-nanofibra es muy superior a la que presenta el material con fibra de carbono, lo cual se traduce en una mayor sensibilidad del composite.The contact area matrix-nanofiber is much higher than the one presented the material with carbon fiber, which translates into greater composite sensitivity
Tradicionalmente la línea de investigación de los materiales cementicios empleados en obra civil y edificación ha estado orientada al estudio de sus propiedades mecánicas debido a su principal y única función estructural. No obstante, últimamente ha surgido una nueva tendencia en esta línea; la integración de otras propiedades que le permitan tener funciones complementarias, convirtiéndose en materiales "multifuncionales".Traditionally the research line of the cementitious materials used in civil works and building has been oriented to the study of its mechanical properties due to its Main and only structural function. However, lately it has a new trend emerged in this line; the integration of others properties that allow it to have complementary functions, becoming "multifunctional" materials.
Existen diversas categorías dentro de los materiales cementicios "multifuncionales"; una de ellas son los materiales cementicios conductores.There are various categories within "multifunctional" cementitious materials; one of them are conductive cementitious materials.
Las propiedades eléctricas se consiguen mediante adiciones conductoras como los materiales carbonosos (por ejemplo, polvo de grafito, fibras de carbono o nanofibras de carbono).The electrical properties are achieved by conductive additions such as carbonaceous materials (for example, graphite powder, carbon fibers or carbon nanofibers).
Esta invención plantea la viabilidad del uso de nanofibras de carbono en matrices cementicias: pastas, morteros y hormigones, a fin de usar dichos composites en la monitorización de deformaciones, es decir de detectar su propia deformación al verse sometidos a acciones externas sin ningún tipo de sensor embebido o adherido.This invention raises the feasibility of using Carbon nanofibers in cementitious matrices: pastes, mortars and concretes, in order to use these composites in the monitoring of deformations, that is, to detect its own deformation when viewed subjected to external actions without any embedded sensor or adhered
Este procedimiento innovador se basa en el cambio en la resistencia eléctrica del material cementicio con adición de nanofibras de carbono al ser sometida a tensiones. De este modo, se realizar un cambio proporcional de la resistencia de contacto de la matriz con la nanofibra con el nivel de tensiones a que es sometida, lo cual es indudablemente interesante a la hora de hablar de una estructura inteligente.This innovative procedure is based on the change in the electrical resistance of the cementitious material with addition of carbon nanofibers when subjected to stress. From in this way, a proportional change in the resistance of contact of the matrix with the nanofiber with the stress level at which is submitted, which is undoubtedly interesting at the time of Talk about an intelligent structure.
La función de percepción de la deformación mediante adición de nanofibras de carbono consiste en que al someter al material a una compresión, esta resistencia de contacto entre la matriz cementicia y la nanofibra disminuye, produciendo a su vez el descenso de la resistencia eléctrica global en la dirección del esfuerzo. Mientras que si la tensión aplicada es de tracción el fenómeno generado es el contrario.The deformation perception function by adding carbon nanofibers is that when submitting to the material at a compression, this contact resistance between the cementitious matrix and nanofiber decreases, producing in turn the decrease in global electrical resistance in the direction of effort. While if the tension applied is tensile the phenomenon generated is the opposite.
Si la tensión aplicada sobrepasa el límite elástico del material se observan efectos irreversibles en la respuesta de su resistencia eléctrica. En ese caso, la capacidad de percibir la deformación del material no es capaz de recuperar totalmente su valor inicial de resistencia ya que en ese nivel tan elevado de tensión ya se han producido dos cambios irreversibles, el fallo del anclaje nanofibra-matriz y la rotura de algunas de las nanofibras.If the applied voltage exceeds the limit elastic material irreversible effects are observed in the response of its electrical resistance. In that case, the ability to perceive the deformation of the material is not able to recover totally its initial resistance value since at that level so high tension there have already been two irreversible changes, the nanofiber-matrix anchor failure and breakage of Some of the nanofibers.
El desarrollo de este composite cementicio permite diferentes aplicaciones prácticas: control de vibraciones estructurales, monitorización de tráfico pesado, detección de movimiento en estancias y seguridad de edificios, en tiempo real, entre otros.The development of this cementitious composite Allows different practical applications: vibration control structural, heavy traffic monitoring, detection of movement in rooms and security of buildings, in real time, among others.
En la Figura 1 se representa una probeta prismática de dimensiones 4x4x16 cm. Esta probeta utilizada en la invención esta fabricada con pasta de cemento Pórtland y nanofibra de carbono del tipo stacked-cup, con un diámetro exterior que varía entre los 20 y 80 nm y un gran hueco central. Dichas nanofibras presentan una relación de aspecto muy alta, con una longitud de varias micras. El método de medida consiste en introducir la corriente por la cara superior 1 y la cara inferior 2 de la probeta y la diferencia de potencial se tomó entre los puntos 3 y 4. A partir de los valores de caída de potencial entre los puntos 3 y 4, se calcula la variación de las resistividades correspondientes.Figure 1 shows a test tube prismatic dimensions 4x4x16 cm. This test tube used in the invention is made with Portland cement paste and nanofiber carbon stacked-cup type, with a diameter exterior that varies between 20 and 80 nm and a large central hole. These nanofibers have a very high aspect ratio, with a length of several microns. The measurement method consists of introduce the current through the upper face 1 and the lower face 2 of the specimen and the potential difference was taken between the points 3 and 4. From the potential drop values between the points 3 and 4, the variation of the resistivities is calculated corresponding.
En la Figura 2 se representa un ejemplo del comportamiento de la invención donde se muestra la evolución de la resistencia eléctrica en función de la deformación durante un ensayo de compresión axial. Probeta 4x4x16 cm de pasta de cemento con adición 5% de nanofibra de carbono, amplitud de carga de 4000 N y velocidad 100 N/s.An example of the behavior of the invention where the evolution of the electrical resistance as a function of deformation during a test axial compression Probeta 4x4x16 cm of cement paste with 5% carbon nanofiber addition, 4000 N load amplitude and speed 100 N / s.
En la Figura 3 se recoge la relación entre el incremento unitario de resistencia eléctrica y la deformación unitaria en un ensayo de compresión axial. Probeta 4x4x16 cm de pasta de cemento con adición 5% de nanofibra de carbono, amplitud de carga de 4000 N y velocidad 100 N/s.Figure 3 shows the relationship between the unit increase of electrical resistance and deformation unitary in an axial compression test. 4x4x16 cm test tube cement paste with 5% carbon nanofiber addition, amplitude of 4000 N load and 100 N / s speed.
Esta realización se proporciona a modo de descripción detallada para cubrir completamente el alcance de la invención para los expertos en la técnica.This embodiment is provided by way of Detailed description to fully cover the scope of the invention for those skilled in the art.
La invención consiste en el uso de nanofibras de carbón en matrices cementicias: pastas, morteros y hormigones, con el objetivo de desarrollar la función de percepción de la deformación y así poder detectar su propia deformación al verse sometidos a acciones externas sin ningún tipo de sensor embebido o adherido.The invention consists in the use of nanofibers of coal in cementitious matrices: pastes, mortars and concrete, with the objective of developing the perception function of the deformation and thus be able to detect its own deformation when viewed subjected to external actions without any embedded sensor or adhered
En cuanto a los materiales utilizados y preparación de las probetas, se han considerado probetas prismáticas de dimensiones 4x4x16 cm con pasta de cemento Pórtland y nanofibra de carbono del tipo stacked-cup, con un diámetro exterior que varía entre los 20 y 80 nm y un gran hueco central. Dichas nanofibras presentan una relación de aspecto muy alta, con una longitud de varias micras.As for the materials used and preparation of the specimens, prismatic specimens have been considered 4x4x16 cm dimensions with Portland cement paste and nanofiber carbon stacked-cup type, with a diameter exterior that varies between 20 and 80 nm and a large central hole. These nanofibers have a very high aspect ratio, with a length of several microns.
Los componentes básicos utilizados han sido:The basic components used have been:
- \bullet?
- Cemento tipo CEM I 52.5 R.Cement type CEM I 52.5 R.
- \bullet?
- Relación agua cemento a/c=0.5.Cement water ratio a / c = 0.5.
- \bullet?
- Cantidad nanofibra de carbono añadida a la mezcla: 5% respecto masa de cemento.Carbon nanofiber amount added to the mixture: 5% with respect to cement mass.
- \bullet?
- Plastificante (SIKA) en proporción variable.Plasticizer (SIKA) in variable proportion
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Las probetas se curaron sumergidas en agua durante 28 días antes de ser ensayadas.The specimens were cured submerged in water for 28 days before being tested.
Después se montaron los componentes eléctricos. Se pintaron bandas de pintura de plata 5 alrededor de las probetas para lograr un buen contacto eléctrico entre el monitor de potencial y la probeta del composite, entonces se rodearon con hilo de cobre 6 firmemente para tener un punto claro de anclaje entre el monitor de potencial y la probeta y que asegure además el contacto eléctrico entre el monitor de potencial y la pintura de plata. La cara superior 1 y la cara inferior 2 también se cubrieron con pintura de plata.Then the electrical components were mounted. 5 silver paint bands were painted around the specimens to achieve good electrical contact between the potential monitor and the composite test tube, then they were surrounded with 6 copper wire firmly to have a clear anchor point between the monitor potential and the test tube and also ensure the electrical contact Between the potential monitor and the silver paint. Face upper 1 and lower face 2 were also covered with paint silver.
En cuanto a los instrumentos de ensayo, la carga de las probetas se realizó mediante una prensa electromecánica modelo EMI/100/FR, suministrada por Microtest S.A. La resistencia eléctrica se midió gracias a un multímetro digital Keithley 2002 suministrado por National Instruments Inc. La intensidad de corriente fue aplicada mediante una fuente externa Keithley 6021 suministrada por National Instruments Inc.As for the test instruments, the load of the specimens was performed using an electromechanical press EMI / 100 / FR model, supplied by Microtest S.A. The resistance electrical was measured thanks to a 2002 Keithley digital multimeter supplied by National Instruments Inc. The intensity of current was applied by an external source Keithley 6021 supplied by National Instruments Inc.
Los diferentes ensayos realizados consistieron en monitorizar la resistencia eléctrica de la probeta en la dirección longitudinal mientras se aplicaban ciclos de compresión también longitudinalmente. El valor máximo de carga aplicado en cada ciclo fue de 4 kN, este valor corresponde a menos de un 25% de la carga de rotura del material compuesto, situándose en un punto intermedio dentro de la zona de deformación elástica del composite, en la cual el comportamiento es óptimo y reversible. La velocidad de carga y descarga fue de 100 N/s ya que se evita que una carga más acelerada produzca efectos similares a impactos, lo cual se traduciría en daños irreversibles al composite. Valores menores de velocidad de carga alargan en exceso el ensayo del material. La intensidad de corriente aplicada fue de 0.1 mA ya que valores superiores producirían la polarización de la disolución intersticial del composite (lo cual enmascara la medida), evitando asimismo reacciones electroquímicas indeseables sobre los electrodos que también afectan al composite y a la monitorización de la deformación. Valores menores de corriente reducían significativamente la sensibilidad del composite al ensayo realizado.The different tests performed consisted of in monitoring the electrical resistance of the specimen in the longitudinal direction while applying compression cycles also longitudinally. The maximum load value applied in each cycle was 4 kN, this value corresponds to less than 25% of the breaking load of the composite material, standing at a point intermediate within the elastic deformation zone of the composite, in which the behavior is optimal and reversible. The speed of loading and unloading was 100 N / s since it prevents a load more accelerated produce effects similar to impacts, which would result in irreversible damage to the composite. Values less than loading speed excessively extend the material test. The applied current intensity was 0.1 mA since values higher would produce polarization of the interstitial solution of the composite (which masks the measurement), also avoiding undesirable electrochemical reactions on the electrodes that they also affect the composite and the monitoring of the deformation. Lower current values reduced significantly the sensitivity of the composite to the test accomplished.
El nivel de percepción de la deformación viene caracterizado por el factor de galga (FG). Este parámetro se define como el cambio fraccional de la resistividad por unidad de deformación (\varepsilon). La siguiente ecuación muestra tal relación:The level of perception of deformation comes characterized by the gauge factor (FG). This parameter is defined. as the fractional change of resistivity per unit of deformation (ε). The following equation shows such relationship:
En donde FG es el factor de galga, \Delta\rho es al variación de resistividad [ohm\cdotcm], \rho es la resistividad inicial [ohm\cdotcm], y \varepsilon es la deformación aplicada (\varepsilon = \DeltaL/L, siendo L la longitud de la probeta).Where FG is the gauge factor, \ Delta \ rho is the resistivity variation [ohm \ cdotcm], \ rho is the initial resistivity [ohm \ cdotcm], and \ varepsilon is the applied strain (ε = ΔL / L, where L is the test tube length).
Según las referencias consultadas, la magnitud de las deformaciones es muy pequeña, midiéndose por este motivo la resistencia eléctrica en lugar de la resistividad. Las medidas de deformación se realizaron utilizando galgas extensométricas sobre la superficie de las probetas.According to the references consulted, the magnitude of the deformations is very small, measuring for this reason the electrical resistance instead of resistivity. The measurements of deformation were performed using strain gauges on the surface of the specimens.
El método de medida consiste en introducir la corriente entre las cara superior 1 y la cara inferior 2 de la probeta y la diferencia de potencial se tomó entre los puntos 3 y 4. A partir de los valores de caída de potencial entre los puntos 3 y 4, se calcula la variación de las resistividades correspondientes. La deformación se calculó como la media de los valores registrados por cuatro galgas extensométricas que se situaron en el punto central de cada una de las caras laterales de las probetas, para de esta forma, tener un valor más fiable de la deformación real durante el ensayo de carga.The method of measurement is to introduce the current between the upper face 1 and the lower face 2 of the test tube and the potential difference was taken between points 3 and 4. From the potential drop values between points 3 and 4, the variation of the corresponding resistivities is calculated. The deformation was calculated as the average of the recorded values by four strain gauges that were located at the point center of each of the side faces of the specimens, for this way, have a more reliable value of the actual deformation during The load test.
Las probetas usadas en estos ensayos se almacenaron en un ambiente con humedad relativa del 100% hasta que se estabilizó su peso. La resistividad inicial de las probetas (empleando un método de cuatro puntas) fue aproximadamente de 1575 ohm\cdotcm.The specimens used in these tests are stored in an environment with 100% relative humidity until its weight stabilized. The initial resistivity of the specimens (using a four-pointed method) was approximately 1575 ohm \ cdotcm.
A continuación se muestran los resultados obtenidos después del curado en cámara húmeda.The results are shown below. obtained after curing in a humid chamber.
En la Figura 2 se muestra la evolución de la resistencia eléctrica de una probeta de pasta de cemento con un 5% de adición de nanofibra de carbono con la deformación que sufre dicha probeta al ser sometida a un esfuerzo de compresión axial. Se usó esta proporción de nanofibra ya que tras estudios iniciales, el comportamiento óptimo del composite desde el punto de vista de la monitorización de la deformación se obtenía para esta cantidad. Deformaciones negativas se corresponden con compresiones de la probeta. Como se puede observar, existe una clara relación entre ambos parámetros, a medida que se comprime la probeta se produce una disminución de su resistencia eléctrica, lo cual permite la posibilidad de establecer una relación entre ambos parámetros.Figure 2 shows the evolution of the electrical resistance of a 5% cement paste test tube of addition of carbon nanofiber with the deformation it suffers said test tube when subjected to an axial compression stress. Be used this proportion of nanofiber since after initial studies, the optimal behavior of the composite from the point of view of the Deformation monitoring was obtained for this amount. Negative deformations correspond to compressions of the test tube. As you can see, there is a clear relationship between both parameters, as the specimen is compressed a decrease in electrical resistance, which allows possibility of establishing a relationship between both parameters.
Por otra parte, también se puede apreciar una reversibilidad del comportamiento entre los distintos ciclos de carga a los que es sometida la probeta. Cuando cesa el estado de carga, la resistencia eléctrica de la probeta recupera su valor inicial. Este comportamiento es crítico a la hora de poder tener una buena fiabilidad en la función de percepción de la deformación. La probeta utilizada es 4x4x16 cm de pasta de cemento con adición 5% de nanofibra de carbono, amplitud de carga de 4000 N y velocidad 100 N/s.On the other hand, you can also appreciate a reversibility of behavior between the different cycles of load to which the test piece is subjected. When the state of load, the electrical resistance of the specimen recovers its value initial. This behavior is critical when it comes to having a Good reliability in the deformation perception function. The test tube used is 4x4x16 cm of cement paste with 5% addition of carbon nanofiber, load amplitude 4000 N and speed 100 N / s
En la Figura 3 se muestra la relación entre el incremento unitario de resistencia eléctrica y la deformación unitaria en un ensayo de compresión axial. Probeta de pasta de cemento con 5% de adición de nanofibra de carbono. De la pendiente de dicha relación se obtiene el parámetro que caracteriza la sensibilidad de la función de percepción de la deformación.Figure 3 shows the relationship between the unit increase of electrical resistance and deformation unitary in an axial compression test. Test tube cement with 5% carbon nanofiber addition. Of the slope from this relationship the parameter that characterizes the Sensitivity of the deformation perception function.
Claims (3)
- a.to.
- Una matriz cementicia basa en la mezcla de cemento, agua y áridos, presentando esta matriz durante las primeras horas naturaleza plástica, lo que permite darle forma, y que tras un determinado tiempo de varias horas (fraguado) se transforma en un material rígido sensible a las deformaciones.A cementitious matrix based on the mixture of cement, water and aggregates, presenting this matrix during the first hours of nature plastic, which allows shaping, and that after a certain time of several hours (setting) is transformed into a material Rigid sensitive to deformations.
- b.b.
- Un 5% de nanofibra de carbono respecto a la masa de cemento que se adiciona a los componentes de la matriz cementicia previamente a su amasado.5% of carbon nanofiber with respect to the cement mass that is add to the components of the cement matrix prior to its Kneading
- c.C.
- Dos contactos eléctricos de pintura de plata aplicada en los extremos de la probeta de composite endurecida que permiten la aplicación de una corriente eléctrica.Two electrical contacts of silver paint applied at the ends of the hardened composite specimen that allows the application of a electric current.
- d.d.
- Dos contactos eléctricos de pintura de plata e hilo de cobre situados perimetralmente en la probeta de composite que permiten la monitorización de la caída de potencial, y en consecuencia de la resistencia eléctrica.Two Silver paint and copper wire electrical contacts located perimeter in the composite specimen that allow monitoring of the potential drop, and consequently of the electric resistance.
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| ES200901735A ES2353544B8 (en) | 2009-08-05 | 2009-08-05 | COMPOSITE CEMENTICIO WITH CARBON NANOFIBRAS FOR MONITORIZATION OF DEFORMATIONS. |
| PCT/ES2010/000341 WO2011015689A2 (en) | 2009-08-05 | 2010-08-02 | Cementitious composite with carbon nanofibers for monitoring deformations |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| ES2403134A1 (en) * | 2011-11-07 | 2013-05-14 | Universidad De Alicante | Cementitious composite having carbon nanofibres for heating |
| ITUA20162508A1 (en) * | 2016-04-12 | 2017-10-12 | Safecertifiedstructure Ingegneria S R L | Survey method and device for measuring stresses in an agglomerate structure |
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| CN109406582A (en) * | 2018-12-28 | 2019-03-01 | 南水北调东线总公司 | A kind of Structure Damage Identification using carbon fiber change in resistance |
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| EP0718252A2 (en) * | 1994-12-19 | 1996-06-26 | Mitsubishi Chemical Corporation | Carbon fibre-reinforced concrete and method for preparing the same |
| US5817944A (en) * | 1996-03-19 | 1998-10-06 | The Research Foundation Of State University Of New York | Composite material strain/stress sensor |
| US6079277A (en) * | 1997-12-12 | 2000-06-27 | The Research Foundation Of State University Of New York | Methods and sensors for detecting strain and stress |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0718252A2 (en) * | 1994-12-19 | 1996-06-26 | Mitsubishi Chemical Corporation | Carbon fibre-reinforced concrete and method for preparing the same |
| US5817944A (en) * | 1996-03-19 | 1998-10-06 | The Research Foundation Of State University Of New York | Composite material strain/stress sensor |
| US6079277A (en) * | 1997-12-12 | 2000-06-27 | The Research Foundation Of State University Of New York | Methods and sensors for detecting strain and stress |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| ES2403134A1 (en) * | 2011-11-07 | 2013-05-14 | Universidad De Alicante | Cementitious composite having carbon nanofibres for heating |
| WO2013068615A1 (en) * | 2011-11-07 | 2013-05-16 | Universidad De Alicante | Cementitious composite having carbon nanofibres for heating |
| ITUA20162508A1 (en) * | 2016-04-12 | 2017-10-12 | Safecertifiedstructure Ingegneria S R L | Survey method and device for measuring stresses in an agglomerate structure |
| WO2017178985A1 (en) * | 2016-04-12 | 2017-10-19 | Safecertifiedstructure Tecnologia S.R.L. | Method and investigation device for measuring stresses in an agglomerate structure |
| JP2019514005A (en) * | 2016-04-12 | 2019-05-30 | セイフサーティファイドストラクチャー テクノロジア エス．アール．エル． | Method and apparatus for measuring the stress of aggregate structures |
| US11118999B2 (en) | 2016-04-12 | 2021-09-14 | Safecertifiedstructure Tecnologia S.R.L. | Method and investigation device for measuring stresses in an agglomerate structure |
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| WO2011015689A2 (en) | 2011-02-10 |
| WO2011015689A3 (en) | 2011-03-31 |
| ES2353544B2 (en) | 2011-09-15 |
| ES2353544B8 (en) | 2019-04-22 |
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